1. Field of the Invention
The present invention relates to a lightweight contoured structure such as an airfoil or hydrofoil.
2. Description of the Prior Art
Conventional airfoils such as airplane wings or helicopter rotor blades are frequently constructed from a series of ribwork generally defining the overall contour and covered with aluminum skin which is riveted to such ribwork. Contoured structures of this type suffer the shortcoming that they are relatively expensive to manufacture and do not have good load carrying characteristics. Many efforts have been made to improve conventional wing structures of this type.
Helicopter rotor blades have been proposed which include a plurality of coextensive tubular cells constructed of tubes formed with woven fiber glass walls and which are covered by a fiber glass skin to form the outline of an airfoil. Such an arrangement is shown in U.S. Patent No. 3,028,292. Airfoils of this type suffer the shortcoming that the tubular members cannot carry high bending stresses to which rotor blades are normally subjected.
Further, turbine blades have been proposed which include a thin metal skin filled with a sponge-like core and having lightening cavities formed therein by means of coextensive aluminum tubes. An arrangement of this type is shown in Great Britian Pat. No. 720,956.
Applicants are not aware of any prior art air-foil structure which takes advantage of the high strength characteristic of fine filament employed in winding processes to provide a practical foil structure.